I still don't know who HH is. Probably couldn't pick him out of a line up of 3, unless his face suddenly invoked memory of a previous meeting. But based in information I have learned today, we probably have a mutual friend/acquaintance. That is likely the answer to your question.
I don't think the guy should be questioned like he is on trial for simply saying he met or knew me 16-17 years ago. But if you do, then I guess you should ask him.